Alternating current dynamo



(No Model.)

G. PFANNKUCHE.

v ALTERNATING CURRENT DYNAMO.

No. 407,875. Patented July 30, 1889.

UNITED STATES PATENT OEEIcE.

GUSTAV PFANNKUOI-IE, OF CLEVELAND, OHIO, ASSIGNOR TO THE BRUSH ELECTRIC COMPANY, OF SAME PLACE.

ALTERNATING-CURRENT DYNAMO.

SPECIFICATION forming part of Letters Patent No. 407,875, dated July 30, 1889.

Application filed December 2. 1887.

To all whom it may concern.-

Be it known that I, GUSTAV PEANNKUCHE, of Cleveland, in the county of Ouyahoga and State of Ohio, have invented certain new and useful Improvements in Alternating-Current Dynamos; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention has reference to improvements in alternating-current dynamos, the object being to render such dynamos self-eX- citing and self-regulating, analogous in this respect to compound constant-potential continuous-current dynamos, whereby the same become adapted for the operation of a system of distribution in which a constant difference of potential is required.

Myimproved dynamo is specially designed for use with such systems of distribution in which the translating devices are in multiplearc branches derived from a main or trunk line, and in which it is designed to maintain a constant difference of potential at the terminals of the derived branches or working-circuits, which are frequently at great distances from the generator. In such systems the difference of potential at the brushes of the generator is dependent upon the relation of the external resistance to the total resistance in such manner that when the external resistance increases, the difference of potential at the brushes also increases, While at the same time less current is generated in the armature, and when the external resistance decreases, the diiference of potential at the brushes also decreases, and more current is at the same time generated in the armature. From this it becomes clear that in a multipleare system of distribution whenever one or more working-branches are opened provision should be made to decrease the strength of the field-magnets, and Whenever additional working-circuits are closed the strength of the field-magnets should be increased, in order to maintain a constant difference of potential. In continuous-current dynamos this result is accomplished automatically by providing the field-magnets with two sets of coils,

fierial'No. 256,815. (No model.)

one set of which is in series with the armature-coils and the other set in a shunt across the brush-terminals of the dynamo, and the manner in which such dynamos operate to maintain a constant difference of potential under the varying resistance of the external circuit is so well understood by those skilled in the art that a specific explanation is deemed unnecessary.

In alternating-current dynamos it has heretofore been deemed impracticable to apply the principles of the compound continuouscurrent dynamo, and in order to adapt alterliming-current dynamos to the'feeding of a system of distribution in which a constant difference of potential is required I have de- -vised certain combinations of such dynamos with separate exciters, which combinations I have made the subject of separate applica tions.

The present invention has for its object the construction of self-exciting alternating-current dynamos in which the same principles are invoked which form the basis of the compound continuous-current dynamo, whereby separate exciters are made unnecessary, the construction simplified, and the effective operation rendered more certain and more economic.

In the accompanying drawing, which forms a part of this specification, I have illustrated my invention mainly in diagram, omitting such details as are readily and necessarily implied.

The alternating-current generator 1 may be of any ordinary or improved construction. It is represented in the drawing as mounted upon a base or platform 2, upon which standards 8 3 of iron are bolted, which constitute the yokes of the field-magnets. The armature 4, which is preferably of the Brush type, is mounted upon a shaft 5, which may be journaled in the standards, and is driven in any suitable manner.

The alternating currents generated in this machine are collected by brushes 6 6, bearing upon collecting-disks '7 7, secured to but in sulated from the shaft and having the terminals of the armature-coils connected therewith. All these parts may be of ordinary construction, well understood by those skilled in the art, and need not be specifically described.

There are two sets of coils upon the debt magnets, one set 8 8 being connected in series with the working-circuit and the other set 9 9 in a shunt around the same, as will hereinafter more fully appear. Upon the part of the armature-shaft which projects beyond the frame of the machine are mounted three commutators 1t), 11, and. 12 side by side and each insulated from the shaft. Each of these conimutators is composed of two hollow cylindrical blocks 10 10 ll 11 and 12 12 respectively, each of which blocks is provided at one end with a number of segmental teeth. alternating with segmental spaces, and these two blocks are so mounted upon the arma-- ture-shaft that the teeth of one engage the corresponding spaces on the other with insulating material, indicated by heavy lines, intervening between the two blocks.

There are two pairs of brushes for each commutator one pair bearing upon the segn'lental portions and the other pair upon the continuous cylindrical portions thereoland in. the further description these brushes will be referred to as alternatordnrushes and straightener-brushes, respectively.

The alteriiator-brushes 115 15 of commutator 11. are connected with wires 1.) 1!), respectively, which are in turn connected with collecting brushes (i. The alternatorbrushes 13 iii) of commutator [10 are connected, respectively, with slumtavires 2o 20, which, as will be seen, are across the wires 19 19, or, in other words, across the brnshterminals oi. the generator. The alternatorbrushes 1? 17 of comn'iutator 12 are connected with the main or trunk-line 2]. 2.1., which is tapped at points 22 253, &c., by multiple-arc branches, in. which suitable translating devices 23 223, &c., are included.

One straightener-hrush 1c of commutator 11 is connected by a wire J-l with straightener-brush 18 of commutator '12, and the other straightener-brush I16 of commutator 11v is connected by a wire 25 with one terminal oi": the set of lield'coils 8, the other termi nal of which is connected by a wire 26 with straightener-brush 18 ot' commutator 19.

Straightener-brush 14: of commutator 1.0 is connected by a wire 27 with one terminal of the set of field-coils f), the other terminal of which is connected by a wire 28 with straightenenbrush 14: of said comn'iutator.

It must be umltnstood that the total number of segments of each of the commutators is equal to the numbcrol alternations of current in the generator, and that they are so located upon shaft relative to the coils of armature 4: that one ol' the alternator-brushes of each of these commutators will bear upon a segment of one of the blocks of which it is composed, while the other of these brushes will bear upon a segment of the other of the blocks during the prevalence of one electr' fill impulse.

The circuits can now be easily traced, and the operation will be readily understood.

The alternating currents generated in the arn'lature t will leave the same alternately by wires 19 and reaching commutator ll. by one of the alternato1.'-brushes 15. IlEy the operation ot this conunntator, which is so well untlerstotnl by those skilled .in the art that it. need not here be explained, the altm-nating impulses are straightened out, and, leaving by straiglitener-lnrnsh 16 as a continuous current, the latter passes by wire to and through the set of coils S 8 ol' the .tieldanagnets and by wire 20 to commutator '12. The continuous current enters this commutator by straightcner-brush l8, andv being now again resolved into alttn-nating impulses the latter pass to line andv multiple-arc branches 2'3 22 alternately by brushes l7 l7, returning by the other of these brushes, and then by brush 1b and wire to brush it? of commutator ll, from whence they return by one or the other ot' altcrnator-ln-nshes 115 15', and one or the other of thewires Iii! .lll to the armature -.l. The course of the currents generated in the armature thus far described is analogousto the course ol a continuous current in an ordinary series dynamo, for it will. be observed that the armature, the set of field-coils S 8, and the main or trunk line 21 21 are all connected in series. 'llmre is, however, this important dil'tcrtnicc, that while in the ordinary dynamo the current travtn'sil'ig the machine and the line is a continuous one, the generator here descrilied furnishes allernating impulses, which are collected. and straightened out before they reach the holdcoils. The contiinious current is then again resolved into alternating impulses which traverse the line. A portion ot the alternating currents, passing by wires 1!) 1!) to commutator ll, diverted to commutator lit) by wires 20 and 20. These divtn'ted currtmts reach the connnutatmf it) by alttn-natorbrushes 13 123, and being straightened out by the operation ol' said. commutator, the continuous current passes by brush 14' and wire 29 to and through the set ol' field-mils S) i), which it leaves by wire 27, returning to the comnuitator by brush 1 -t. This circuit is a shunt across the terminals of the generator, and, as has been seen, it includes the second set i) 9 ol' the lield-coils,which are charged in the same sense as the first set S S ol the fieldcoils, so that the two sets combine to energize the field similar in this respect to the operation ol: the ordinary continnous-current compound dynamo. The regulating ell'ect of this self-exciting alternatingcurrcnt generator is also snbstantiallythc same as that of an ordinary compound dynamo, as will now be clear to those skilled. in the art. If one or more working-circuits are cut out, the external resistance is increased, the total resistance is also increased, but the relation of the external resistance to the total resistance is so varied that the difference of potential is also increased, while less current is generated in the armature and traverses wires 19 19. The charge of the series coils of the field is therefore weakened, while, by reason of the increased difference of potential more current is diverted into the shunt-coils but the aggregate amount of current to the two sets of field-coils is diminished and the strength of the field is decreased. Consequently the difference of potential is lowered. If, on the other hand, more working branches are closed and both the external and total resistances decreased, the relation of the external resistance to the total resistance is so varied that the difference of potential is decreased, while more current is generated in the armature and traverses wires 19 19. The charge of the series coils of the field is therefore increased, while, by reason of the diminished difference of potential, less current than before is diverted into the shunt-coils but the aggregate amount of current to the two sets of field-coils is increased and the field is strengthened. Consequently the difference of potential is increased. Thus it will be seen that any change in the system that tends to vary the difference of potential will react upon the dynamo to cause the same to automatically re-establish the original difference of potential.

Alternating current generators are ordinarily constructed to furnish currents of comparatively very high tension, which currents can be sent to great distances over comparatively thin conductors. Such currents, however, are not well adapted for the operation of the more common translating devices, like motors, lamps, &c., and these currents should be transformed before they reach the motors or lamps into currents of comparatively low tension. For this purpose any suitable transformer may be used, and in the drawings I have shown induction -transformers 23 23, 850., with their primary coils in the multiplearc branches 22 22 and their secondary coils in the working-circuits proper; but it will be understood that I am not limited to this arrangement, since any other suitable translating devices adapted to be operated by hightension currents may be substituted for the induction-transformers. It is also practicable to generate currents of comparatively low tension in the dynamo, in which case lamps or motors or other translating devices may take the places of the inductoriums in the multiple-arc circuits 22 22.

Numerous changes may be made in the arrangement of the parts of the dynamo without departing from the principle of my invention. It is, for instance, evident that cylindrical block 11 of commutator 11 may be made in one piece with cylindrical block 12 of commutator 12, in which case straightenerbrushes 10 and 18' and connecting-wire 24. are dispensed with.

If it is desired to have a continuous current upon the main line, the whole of commutator 12 may be removed and the line extended from wires 24 and 26, as indicated in the drawings by dotted lines21 21 or both circuits may be used, if desired. Other changes of this and a similar character will suggest themselves spontaneously to those skilled in the art, and I desire it to be understood that I do not limit my invention by the identical details of construction herein shown and described.

Having now fully described my invention, I claim and desire to secure by Letters Patent 1. In a self-exciting alternating-current compound dynamo, the combination, with the armature, of field-magnets having two sets of field-coils wound to act cumulatively in energizing the field, one coil being in series wit-h the working-circuit and the other in a derived circuit, and a separate commutator for each set of coils, said commutators being constructed to straighten the alternating current generated by the dynamo and transform it into two continuous currents for use in energizing the two sets of field-coils, substantially as set forth.

2. In a self -exciting alternatingcurrent dynamo, the combination, with a generatingarmature and collectors for taking the alter nating electrical impulses from the same, of two sets of field-coils and a separate commutator for each set for straightening the alternating exciting-currents to each coil, and an independent commutator for resolving the straightened current into altern atingimpulses to the line, substantially as described.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

GUSTAV PFANNKUCHE.

Witnesses:

ALBERT E. LYNCH, PAUL KISTER. 

